CZ20002290A3 - Electrochromic device, UV-protected - Google Patents

Abstract

The electrochromic device is protected against UV radiation by nanoparticles.

Description

Electrochromic device, protected against UV radiation

Technical field

The present invention relates to an electrochromic device protected against UV radiation.

State of the art

Electrochromic devices are already known, for example from the publication by D. Theise in Ullmann’s Encyclopedia of Industrial Chemistry, Vol. A8, p. 662, Verlag Chemie 1987 and VO-A 94/23333. Two basic types are distinguished:

Type 1: Full-surface electrochromic devices.

Type 2: Electrochromic display devices with structured electrodes.

Type 1 is used, for example, for electrically darkenable window panes or electrically darkenable car mirrors. These devices are known, for example, from US-A-4,902,108.

Type 2 is used in the case of segmented or matrix displays. These display devices were designed, for example, in German patent application P 196 31 728. Devices of this type can be viewed transmissively (using light transmission) or reflectively (using light reflection from the mirror coating).

• · • ·

I • '» · · ···· · · · » • ·*· · · ·· ··· · · · • « · · · · · · · · ····« · · ·· · · · ·

VO-A 94/23333 compares electrochromic materials of various designs, which are not used as display devices:

Design and:

Electrochromic substances are a film or layer firmly attached to Ullmann (see above).

applied as electrodes (e.g.

Embodiment b: Electrochromic substances are deposited as a layer on electrodes using a reduction-oxidation method (e.g. Ullmann, see above).

Version c:

Electrochromic substances remain permanently in solution.

For embodiment a), the best known electrochromic material is the tungsten oxide/palladium hydride pair.

For embodiment b) viologens have been described as electrochromic substances. These devices are not self-erasing and the image thus created remains after the current is switched off and can be erased again by reversing the polarity of the voltage. These devices are not particularly stable and do not allow a high number of switching cycles.

The cells - and especially those made of tungsten oxide/palladium hydride - cannot be operated by transmitted light, but only reflectively due to the scattering of light on these electrochromic layers.

Elektrochimija, 13, 32-37 (1977), 13, 404-408, 14, • · · e * · • · · · ir

319-322 (1978), US-A 4,902,108 and US-A 5,140,455 describe an electrochromic system of the latter embodiment c). The electrochromic cell, which is formed from conductively coated glass plates, contains a solution of a pair of electrochromic substances in an inert solvent.

As a pair (cell) of electrochromic substances, one electrochemical, reversibly reducible substance and one reversibly oxidizable substance are used. Both substances are colorless or only slightly colored in the ground state. Under the effect of an electric voltage, one substance is reduced and the other substance is oxidized, and both become colored. After the electric voltage is turned off, the ground state of both substances is re-established, which is accompanied by the disappearance or fading of the color.

RED ₁ + ....... * ^OX 1 ⁺ RED ₂ (colorless) (colored) (low energy (high energy pair) pair)

It is known from US-A 4,902,108 that suitable reduction-oxidation cells are those where the reducible substance exhibits at least two chemically reversible reduction waves in a cyclic voltammogram and the oxidizable substance simultaneously exhibits at least two chemically reversible oxidation waves.

According to WO-A 94/23333, however, these solution systems of embodiment c) have serious disadvantages.

Diffusion of electrochromic substances in solution causes imprecise color interfaces and requires high current consumption to maintain the color state, as the colored substances are constantly disturbed by recombination and reaction at the corresponding opposite electrode.

However, various applications have been described for these electrochromic cells of embodiment c. For example, they can be arranged as rear-view mirrors of automobiles, which can be darkened by applying a voltage when driving at night, and thus glare from the headlights of other vehicles can be prevented (e.g. US-A 3 280 701, US-A 4902 108, EP-A 0 435 689). In addition, these cells can be used in window panes or retractable roofs of automobiles, where they block sunlight after applying a voltage. The use of these devices as electrochromic display devices is also described - for example in segmented or matrix displays with structured electrodes (German patent application P 196 31 728).

Electrochromic cells normally consist of a pair of glass plates, one of which is provided with a mirror in the case of automotive mirrors. One side of these plates is coated over the entire surface with a transparent, electrically conductive layer, for example indium tin oxide (ITO), and in the case of display devices this conductive layer is divided into segments which are electrically isolated from each other and are individually connected. These plates are then used to form a cell by connecting them via a sealing ring, the electrically conductively coated sides facing each other to form a cell. This cell is then filled with an electrochromic fluid through the opening and the cell is tightly and hermetically sealed. Both plates are connected to a voltage source by means of two ITO layers.

The electrochromic devices described above are generally sensitive to light, especially UV radiation. As a result • · • · • · · • · * • · · » ♦ · t • · · · · φ 4 · » • 4 4 · φ » 4 4 4

4 4 4 4 4 4 ·

4 4 9 4 1 9 9, for example, electrochromic devices containing UV stabilizers have been described in US-A 5,280,380.

The UV absorbers used so far have mostly been organic compounds that have molecular absorption bands in the relevant wavelength range and do not absorb in the visible spectral range. The disadvantage of these compounds is that they must be dissolved, in some cases in high concentrations, in an electrochromic solution or in a polymer layer applied to one of the two plates. However, the solubility in these media is often limited and, as a result, the efficiency of the UV absorber is limited. In addition, they may fade upon exposure to light and/or be washed out or evaporated from the polymer substrate.

It is also known that inorganic materials in the solid state can absorb UV radiation.

Depending on the size and choice of material, these inorganic particles can scatter and/or absorb areas of harmful UV radiation. In this context, absorption should be preferred to scattering of radiation, since scattered photons, especially when the particles are embedded in the material to be protected, can cause damage to this material. In addition, too large a scattered radiation component leads to clouding of the material to be protected. It is known from the publication Absorption and Scattering of Light by Smáli Particles, C. F. Bohren, D. R. Huffman, pp. 93 to 104 and 130 to 141, 1983, that as the size of the particles decreases, their light absorbance is higher than their light scattering ability. Therefore, only very small particles are suitable for a transparent UV absorber.

To ensure that the UV absorber is colorless, it must • 9 i

• · · · · fl the particle material exhibits an absorption edge in the wavelength range between about 300 nm and 400 nm. According to VO-A 93/06164, suitable materials for this effect are those which have an intrinsic attenuation band between 2.8 eV and 4.1 eV, corresponding to a wavelength range between 303 nm and 445 nm. Materials of this class which have already been used for this purpose include T1O2, ZnO, CeO2 and SiC, see for example VO-A 93/06164, VO-A 95/09895 and VO-A 92/21315.

Consequently, the aim was to provide UV absorbers which do not have the disadvantages known from the prior art and which are highly suitable for protecting electrochromic cells from UV radiation.

The essence of the invention

It has now been found that the electrochromic devices described above can be effectively protected against UV damage by the use of nanoparticles.

The subject of the present invention is therefore an electrochromic device that is protected by nanoparticles against UV radiation.

The subject of the present invention is an electrochromic device consisting of two plates or foils, at least one of which is transparent and which are provided with a conductive layer on the sides facing each other, at least one of which is transparent and are connected to each other by a sealing ring, so that the plates or foils and the sealing ring define a volume inside which there is an electrochromic medium, which is characterized in that the electrochromic device is protected by nanoparticles against UV radiation.

) • · «

Plates are made of glass or plastic materials, and films are made of plastic or special thin glass materials.

In one particular arrangement of the electrochromic device, nanoparticles are present in the electrochromic system and/or are deposited on and/or incorporated into at least one of two transparent plates or foils.

According to the present invention, electrochromic devices in which at least one of the two conductive layers is coated with an electrochromic layer and electrochromic devices in which the electrochromic medium forms an electrochromic solution are particularly preferred, characterized in that the electrochromic device is protected by nanoparticles against UV radiation.

Suitable nanoparticles are compounds based on SiC, AISi,

and GaN, in which 0.7<y<la0<xl<.

Nanoparticles that are particularly suitable in the context of the present invention are materials that are known from the above-mentioned literature and patent applications and are based on TiO ₂ , ZnO, CeO ₂ ,

SiC, AISi, Fe ₂ O ₃ , Fe ₃ O ₄ , ν _χ Μ _Οι _ _χ 0 ₃ ,

BaTiO ₃ , CaTiO ₃ or mixtures thereof.

Particle clouding of the UV absorber is unacceptable for electrochromic devices, as various applications such as automotive mirrors or display devices require high light transmission and particularly precise display. Particles that form radicals are particularly unsuitable for · · β · · · 4· ··

4 4 J» ♦ · ···« «4 4 · «··· · «« · • «4444 44 4 · 4 4« 4 · ···« ·»·· • >444 44 · * 44 · · use when these particles are present in the electrochromic solution. The interaction with the radical or radical ion groups OX^ and RED2, as a rule, formed by the electrode reaction, will interfere with the above-described equilibrium and will lead to undesirable color changes and/or to inappropriate color erasure after switching off the voltage. Particularly preferred are nanoparticles which have a mean diameter of less than 500 nm, preferably less than 100 nm, particularly preferably less than 50 nm and very particularly preferably less than 20 nm.

Very particularly preferred are therefore UV absorbers which predominantly contain silicon particles and/or solid compounds in which silicon is present in stoichiometric excess. A mean diameter of less than 120 nm is preferred. These absorbers have advantageous properties such as high transmittance in the visible spectral range at low particle concentrations, high stability in air, high environmental acceptability and biocompatibility, complete absence of photocatalytic activities and also high efficiency in filtering out radiation in the UVA and UVB ranges.

The mean here means the maximum of the frequency distribution.

Elemental silicon is amorphous or crystalline silicon, preferably crystalline silicon. The size of the silicon particles is preferably between 1 nm and 120 nm, particularly preferably between 1 nm and 70 nm and very particularly preferably between 10 nm and 50 nm. These particles preferably have a size distribution with a maximum mean peak width of 40 nm. Silicon particles having this mean diameter are preferably prepared using a gas phase reaction (CVR) according to the method described in US-A-5,472,477. It is also possible to prepare them according to the method described in the publications J. Phys.

« • ♦ · ·

Chem., 97, pp. 1224-1230 (1973), J. Vac. Sci. Technol.

A10, p. 1048 (1992) and Int. J. Heat Mass Transfer 31, p.

2236 (1988).

The term solid compounds includes compounds that are solid at room temperature, such as silicides, CaSi2 and/or BaSi2. The term compounds in which silicon is present in stoichiometric excess preferably includes compounds of the general formula Si _x Z-^_ _x , where 0.5<xl<aZ=C, N, O, Ge, Ca, Ba and Sr. The presence of other materials shifts the energy position of the absorption edge within certain limits and modifies the shape of the edge. Solid compounds that are preferred in this sense are Si _x C ₁ _ _x or Si _x Ge _lx .

These nanoparticles of all the materials described herein are those that are round or nearly round. Nearly round means, for example, ellipsoids that have an axis ratio of 1:4, preferably 1:2.

Nanoparticles of all the materials described herein which have a core-shell structure are also preferably used. The shell may be organically modified.

For example, the shell consists of an oxide of the material of the nanoparticle. Alternatively, the shell may consist of another material that is transparent in the visible range and has a refractive index similar to that of the nanoparticle. The thickness of the oxide layer may be, for example, between 1 and 300 nm.

In a preferred embodiment of the invention, the solid compounds in which silicon is present in stoichiometric excess have a core-shell structure. Preferably, this structure consists of a core of titanium nitride and a shell of silicon, wherein the object• * «

• * · · ····· 4 · · · · ·« 4

444 · 4 40 0 • 4 «0 0 4 04 · · the amount of silicon is at least 30% per particle.

The mean particle diameter of all types described herein is preferably less than 120 nm, particularly preferably less than 100 nm and very particularly preferably less than 50 nm. These particles have a particle size distribution with a maximum mean peak width of 40 nm, preferably 30 nm and particularly preferably 20 nm.

Solid compounds, including compounds with a shell-core structure, can be prepared, for example, by thermal decomposition of a silicon-containing gas, such as silanes, organosilanes or SiCl4, to obtain an aerosol (see J. Phys. Chem., 97, pp. 1224-1230 (1973), J. Vac. Sci. Technol. A10, p. 1048 (1992). By mixing with other gases, such as germanium or carbon, compounds of the appropriate stoichiometric composition are formed. In the case of solid compounds with a shell-core structure, the core is first prepared by the methods described above and then the shell is applied by decomposition or gas-phase reaction of gases of the appropriate composition, such as SiH4 or SiCl4 together with the. Thermal decomposition can also take place in a reactor and in the gas phase, preferably in a CVR (chemical vapor reaction) reactor or also by using a laser. absorption (see Int. J. Heat Mass Transfer, 31, p. 2239 (1988). Thermal decomposition of gases is particularly suitable for the preparation of crystalline particles. Preparation using the PECVD (plasma enhanced Chemical vapour deposit) method is also possible (see J. Vac. Sci. Technol., A10, p. 1048 (1992). The second method produces amorphous particles which can be converted to crystalline form by subsequent heat treatment (see Nanostructured Materials, Vol. 6, pp. 493 to 496 (1995).

The particles in the UV absorber can also be in the form of ·«·· « · · · · · · · • · · ··«·· · 4 4 · • · · · · · · t · 4 · 4 4 · • · · · 4 · · 4 4 4

4 44 4 4 4 4 4 1 9 4 agglomerates. In the case of silicon, the optical properties of agglomerates differ from those of primary particles because the electromagnetic interaction of the particles with other particles creates new absorption channels, which partly lie in the visible spectral range.

The primary particles in the UV absorber can also be surrounded by an oxide layer. This layer prevents direct contact of the primary particles and thus their agglomeration. The thickness of the oxide layer is preferably from 1 nm to 300 nm, particularly preferably from 10 to 100 nm. Preferred oxide layers are those whose refractive index in the visible spectral range has very similar values to the media to be protected against UV radiation, such as polycarbonates, polyurethanes and organic solutions such as the electrochromic medium. As a result, the light scattering effect is reduced and the matrix remains transparent. This oxide layer can be prepared, for example, by dosing oxygen into the CVR reactor after the preparation of the particles.

In a preferred embodiment, the UV absorber according to the invention additionally contains particles of metal oxides and/or nitrides which absorb more in the red spectral range from 600 nm < lambda < 700 nm than in the blue-green spectral range from 400 nm < lambda < 550 nm. These preferred additives are titanium nitride particles with a mean diameter of from 1 nm to 400 nm, preferably from 10 nm to 120 nm, or agglomerates of primary titanium nitride particles. These particles can be prepared, for example, according to US-A 5,472,477. In a preferred embodiment, the UV absorber contains not only silicon particles but also TiN particles with a mean diameter of from 10 to 120 nm. This UV absorber is highly effective in the UVA range and at the same time ensures color neutrality, combined with high• ♦ ·· • 9

9 »··· · 9 · 9

999 «9 * 9 9« 99 ·· transparency. Preferably, additives in the form of sodium aluminum silicate particles (ultramarine pigments), which are obtainable from Nubiola S.A., under the

D by the designation Nubix pigments. Another additive that the particles may contain is ferric hexacyanoferrate.

In a further embodiment of the invention, the UV absorber preferably consists of a mixture of particles containing silicon and particles from the following group: silicon carbide and/or metal oxides such as titanium, cerium, tungsten, zinc, tin and iron. By using these mixtures, it is possible to adjust the absorption edge and in particular its steepness. The size of the added particles is between 1 nm and 200 nm. These particles are also obtainable, among other things, by using the method described in US-A 5,472,477.

Materials for electrochromic layers are either inorganic layers, such as the tungsten oxide/palladium hydride system described earlier, or organic layers, consisting of, for example, electrochromic substances, as described below for specific application in an electrochromic solution. Oligomeric or polymeric electrochromic substances of this type are particularly suitable for layers, such as electrochromic substance layers, which are kept insoluble, for example by selecting an oppositely charged ion.

The present invention also provides an electrochromic device, which is characterized in that it contains as an electrochromic solution

a) solvent,

b) at least one reversibly oxidizable substance RED^ dissolved in this solvent, which releases electrons to • · ♦ ·· • 449 4 4 · · · · · 4 · ·

9 99·« 9 · 9 ·

9·9 · 4 4 · · · 49 «4 anode and at least one reversibly reducible substance OX ₂ , which accepts electrons at the cathode and thus these substances are converted to their respective forms OX ₄ and RED ₂ , at least one of these electron release or acceptance is associated with a change in absorbance in the visible range of the spectrum and the original forms RED^ and OX ₂ are in each case re-formed after charge equalization and

c) dispersed nanoparticles.

By dispersed particles are meant inorganic solid materials, which are described in more detail above.

By the change in absorbance in the visible range it can be meant that

a) OX ₂ and/or RED^ are colorless or only weakly colored, while the forms RED ₂ and/or OX^ formed at the cathode and anode are colored, preferably strongly colored,

b) at least one of the two electrochromic substances OX ₂ or RED^ is colored, while its forms RED ₂ or OX^, formed at the cathode or anode, are colorless or only slightly colored or have a different color.

By selecting the electrochromic compounds RED^ and OX ₂ and/or their mixtures, it is possible to set any desired monochromatic shades. For polychromatic coloring, it is possible to place two or more of these electrochromic devices two-dimensionally on top of each other, each of which is capable of producing a different shade. A layer of this type is preferably formed so that the devices that are in contact with each other 14 • 9·· · » '' • 9 9 9 9 9 9 99 9

99999 99 99 99 9 • 999· 9 9 9 9 •9 99 9 · 9 9 ·· tact, have a common transparent plate, which is then conductively coated on both sides and divided into segments in accordance with its configuration. The layer will then consist of, for example, three electrochromic devices, which include at least four plates. By switching on the segments in different devices in this layer, it is possible to realize multi-color displays. When the segments of these different devices, which are switched on, lie next to each other, mixed colors are obtained. Therefore, it is possible to create any desired colors in the structure of a three-color system and thus, for example, multi-color images.

OX2 and RED-^ substances which are suitable in the sense of the present invention are those substances which, when reduced or oxidized at the cathode or anode in the said solvent, give the products RED2 and OX^ which do not enter into any subsequent chemical reaction but instead can be completely oxidized or reduced again to give OX2 and RED-^.

The reducible substances OX2 which are suitable for the purposes of the invention are those substances a1) which, in the solvent used in the device, exhibit a cyclic voltammogram which shows at least one, preferably at least two chemically reversible reduction steps;

bl) which represent an organic compound, for example a cyclic organic compound, which, upon receiving 1 or 2 electrons, undergoes cleavage of one of the σ bonds to form a compound, for example an open-chain compound, and which, upon releasing 1 or 2 electrons, returns back to the original - for example cyclic - starting compound.

• ♦··

Oxidizable substances RED^ which are suitable in the sense of the invention are those substances, a2) which in the solvent used in the device show a cyclic voltammogram which shows at least one, preferably at least two chemically reversible oxidation stages;

b2) which represent an organic compound, for example a cyclic organic compound, which, upon releasing 1 or 2 electrons, undergoes cleavage of one of the σ bonds to form a compound, for example an open-chain compound, and which, upon accepting 1 or 2 electrons, returns back to the original - for example a cyclic compound.

In the cyclic voltammogram, the compounds specified in paragraphs bl) and b2) generally exhibit a chemically irreversible reduction or oxidation step followed by a chemically irreversible oxidation or reduction step. In general, two electrons are transferred during the cleavage or formation of a σ bond. However, the compounds specified in paragraphs bl) and b2) should not be limited to those compounds which exhibit the behavior described above in the cyclic voltammogram or in which two electrons are transferred during the cleavage or formation of a σ bond or in which the cleavage or formation of a σ bond is associated with chain opening or closure.

Suitable OX2 compounds within the meaning of the invention are:

• ···

X* φ • · · ·

ΦΦΦ·· φφ φφφ φφ φ φ φφφφ φφφφ • Φ φφ φφ φφ φφ

101 + N-N

103 // \

X(CI),

R

106

105 (Target),

104

X18

• 44 4 · 4 4

4444 4 44 9

4· 94 444 44 9

49 4 9 99 9

44 49 49 (Clil), (CIV), in which r5, r8, R16, r17 _and r19 _{independently} represent an alkyl group with 1 to 18 carbon atoms, an alkenyl group with 2 to 12 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, or

R^; R5 or R®; R^ can together form a -(Cl·^^ ^- or -(CH2)3-bridge,

R^, R? and R^ to R^$ independently represent hydrogen, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, halogen, cyano, nitro or an alkoxycarbonyl group with 1 to 4 carbon atoms, or • · · • · · ··· ·· • · ♦ • · · • · · · · ·

R ²² ; r23 _and / _not ]j _O r24 . r25 _can form a -CH=CH-CH=CH-bridge, rIO; RU, R^ ² ; r!3 _and R ¹⁴ ; R ¹ ^ independently of each other represent hydrogen or in pairs represent

-(CH2)2“> (©^2)3- or -CH=CH-bridge,

R^O and R^l independently of each other represent O, N-CN, C(CN)2 or

an N-aryl group with 6 to 10 carbon atoms,

R ²⁶ and R ²⁷ represent hydrogen, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, halogen, cyano, nitro, an alkoxycarbonyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms, r69 _and r74 independently of each other represent hydrogen or an alkyl group with 1 to 6 carbon atoms, or

R ⁶⁹ ; R ¹² and/or R ⁷⁰ ; R ¹³ together form a -CH=CH-CH=CH bridge, “IO Ί

E ^x and E ^z independently represent 0, S, NR or C(CHj)2 or

E-*· and E ² together form a -N- (CH ₂ ) 2-bridge,

R ⁴ denotes an alkyl group with 1 to 18 carbon atoms, an alkenyl group with 2 to 12 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, denotes a direct bond, -CH=CH-, -C(CH ₃ )=CH-, -C(CN)=CH-,

40 04 00 00

444 0404

0 4 0440 0 44 4

400 00 0« «00 00 4 • 0040 0000 ··· ·0 00 40 04 40

-CC1=CC1-, -C(OH)=CH-, -CC1=CH-, -CC-, -CH=NN=CH-, -C(CH ₃ )=NN=C(CH ₃ )- or -CC1=NN=CC1-,

Z ² represents -(CH ₂ ) _r - or -CH ₂ -C ₆ H ₄ -CH ₂ -, r represents an integer from 1 to 10, up to R ^05 independently represents an aryl group with 6 to 10 carbon atoms or preferably a benzofused or quasiaromatic five- or six-membered heterocyclic chain, r!07, r!09, rH3 _and rH4 independently represent a group of general formula (CV) to (CVII)

(CV), (CVI), (CVII)

X21 • *· • · · φ • Φ *« • · φ φ * φ φφ * γ ρ108, r!15 _and r116 independently of each other denote an aryl group with 6 to 10 carbon atoms or a group of the general formula (CV), rHQ to R^ ²² , r117 _and r118 independently of each other denote hydrogen, an alkyl group with 1 to 4 carbon atoms, halogen or cyano, and Ε^θ ² independently of each other denotes 0, S or NR ²² ^,

11Q 199

R and R independently represent an alkyl group with 1 to 18 carbon atoms, an alkenyl group with up to 8 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, r!06, r!20, r121, r!23 _and r124 independently represent hydrogen, an alkyl group with 1 to 18 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, halogen, cyano, nitro or an alkoxycarbonyl group with 1 to 4 carbon atoms, or

^R120 , ^R121 and/or ^R123 , ^R124 together form a -CH=CH-CH=CH bridge, and

X denotes an anion that is redox inert under the given conditions.

OX2 compounds which are suitable in the sense of the invention are also metal salts or metal complexes, preferably of those metal ions whose oxidation states differ by 1. Examples of suitable OX2/RED2 metal ions are Fe/Fe,

Ni ³⁺ /Ni ²⁺ , Co ³⁺ /Co ²⁺ , Cu ²⁺ /Cu ⁺ .

Suitable RED^ substances within the meaning of the invention are:

(XIII), φ φ • φ φ · φφφ φ

φ ·· • · φ · φ φ · · *

ΦΦΦ C * · * • Φφφ · φ φ φ · · · · · φφ φφφφ

(XIV),

(XV),

(XVI), (XVII),

(XVIII),

(XX), in which up to R

R ¹ , r 53 _and r 54 independently represent an alkyl group with 1 to 18 carbon atoms, an alkenyl group with 2 to 12 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group

group with 7 until 15 group with 6 until 10 33 _years 36 R 37 , R 40

R a R^ _a ž R^S ,41 ,42 ,45 ,47 ,48 r49 to

R , R , to R ^, R , R independently represent hydrogen, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, halogen, cyano, nitro, an alkoxycarbonyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms and

9 » ··

9 9 9 9 <

• · · 9999 9

999 · · 99 999

9 9 9 9 9 «9 ·· ·· • · «

9 *>

«9 9 «

58

R and R ° additionally denote an aromatic or quasi-aromatic five- or six-membered chain, which is preferably benzo-fused and R ⁴ ^ additionally denotes NR ⁷⁵ R ⁷⁶ , or

R ⁴⁹ ; R ⁵⁰ and/or R ²¹ ; R ⁵² form -(CH ₂ ) ₃ -, -(CH ₂ ) ₄ -,

-(CH ₂ ) ₅ - or -CH=CH-CH=CH bridge, and

Z denotes a direct bond or -CH=CH- or -N=N-bridge, =Z ⁴ = denotes a direct double bond or =CH-CH= or =NN= bridge,

E ² to Ε ² , Ε^θ and E^ ⁷ independently of each other denote 0, S, NR ²⁹ or c(ch ₃ ) ₂ ,

E ² additionally denotes C=0 or S0 ₂ ,

E ² and E ⁴ independently of each other may additionally denote -CH=CH-,

E1 to ^E9 independently represent S, Se or ^NR29 ,

R ²⁹ ; R ⁷² and R ⁷ ^ independently of each other denote an alkyl group with 1 to 12 carbon atoms, an alkenyl group with 2 to 8 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms,

0 0 · • 9 9 • 999 · ·

• 9 9 9 9 · 99 · · • 9 9 9 9

9 9 *

9 9 · • 9 9·

9 99 « · · ♦

0· ·

9 9 9 »

9 0 ·

R ²³ additionally denotes hydrogen or R ²³ and R ²³ in definition 7 S Ύ A

NR R', together with the N atom to which they are attached, represent a five- or six-membered chain which optionally contains further heteroatoms, r61 to r68 independently of one another represent hydrogen, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, cyano, an alkoxycarbonyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms and r61; r62 _and p67. p68 independently of one another additionally form

-(CH ₂ ) ₃ -, -(CH ₂ ) ₄ - or -CH=CH-CH=CH bridge, and v represents an integer between 0 and 10.

RED-£ substances which are suitable in the sense of the invention are also metal salts or metal complexes, preferably of those metal ions whose oxidation states differ by 1. Examples of suitable RED^/OX-^ metal ions are Fe ²⁺ /Fe ³⁺ , Ni ²⁺ /Ni ³⁺ , Co ²⁺ /Co ³⁺ , Cu ⁺ /Cu ²⁺ .

Similarly suitable in the sense of the invention are also those redox cells which are interconnected by a covalent bridge of the general formula

Y_[_(_B- _Z -) _a -(-BY-) _b -] _c -BZ (I), in which

Y and Z independently represent the group 0X ₂ or RED^, • » • · » 4 ► ·

44

4 4 4 · where at least one Y represents 0X ₂ and at least one

Z represents RED^ , • ·

4 < 4 4 • 4 ·· « »4 4

4 *

4 4 9 · where

0X ₂ represents a group of reversibly electrochemically redox systems

RED^ represents a group of reversibly electrochemically oxidizable redox systems,

B represents a bridge term, c represents an integer from 0 to 1000, and a and b independently represent an integer from 0 to 100.

Preferably (a+b).c < 10,000.

Reversibly electrochemically reducible or oxidizable in the sense of the invention means that the electron transfer can take place with or without a change in the σ-lattice exclusively in the sense of the above-mentioned definition of OX ₂ and RED^ according to the invention.

Electrochromic compounds of the general formula (I) in particular mean compounds of the general formulae ox ₂ -b-red ₁ (Ia), φ φ · · φ • φ • · φ φφφφ φ φ · φφφ ox ₂ -b-red ₁ -b-ox ₂ red ₁ -b-ox ₂ -b-red ₁ ox ₂ -(B-RED ₁ -B-0X ₂ ) _d -B-RED ₁ (lb) , (lc) or (ld) , in which

0X ₂ , RED^ and B have the meaning given above and ad represents an integer from 1 to 5.

OX ₂ and RED ^ in the general formulas (I) and (Ia) to (Id) mean in particular the groups of the above-described redox systems of the general formulas (II) to (IX), (CI) to (CIV) and (X) to (XX), where the bond to the bridging member B is via one of the groups R to

^R22 to ^R27

R ²⁸ to R ⁵⁸ _r 67

R ⁶⁸ and R ¹²² or

2.1 when one of the groups E or E is NR , or one of the groups

E ³ to E ⁷⁷ is NR ³ ^, or one of the groups Ε^θ ¹ to E ⁷ ® ² is NrII9, is through R ⁷ , R ³ ^ or R ⁷ ^^ and in this case these groups represent a direct bond, and

B represents a bridge of the general formula -(CH ₂ ) _n ~ or

-[Y ¹ s(CH ₂ ) _m -Y ² ] o-(CH 2 ) p Y ³ q -, which may be substituted by an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, halogen or phenyl,

Y ⁷ to Y ³ independently represent 0, S, NR ⁸ ®, C00,

CONH, NHCONH, cyclopentadiyl, cyclohenadiyl, phenylene or naphthylene, • ♦ · · • · ♦ · » r60 represents an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, n represents an integer from 1 to 12, map independently represents an integer from 0 to 8, o represents an integer from 0 to 6 and q and s independently represent 0 or 1.

Examples of metal salts or metal complexes that α_ι o 4.

can be used as 0X3 or RED^ are Fe /Fe , Ni ³⁺ /Ni ²⁺ , Co ³⁺ /Co ²⁺ , Cu ²⁺ /Cu ⁺ , [Fe(CN) ₆ ] ³ -/ ⁴ ,

Fe ₄ [ Fe (CN) g ] ₃ θ ^/Ζ4 ” , [Co(CN)g] ³ ~/ ⁴ “, [Fe(cyclopentadienyl) ₂ ]°/ ⁺ .

Suitable counterions for metal ions and cation complexes are all redox-inert anions X, as described in more detail below, and suitable counterions for anion complexes are all redox-inert cations M ⁺ , examples being alkali metals or quaternary ammonium salts such as Na ⁺ , K ⁺ , N(CH3)4 ⁺ , N( _C4H9 ) ₄ ⁺ , C _ó H ₅ CH ₂ N( _CH3 ) ₃ ⁺ , etc.

Electrochromic devices are preferably used in which

OX ₂ represents a group of general formula (II), (III), (IV) (V) or (CI), in which a 4 cqa

R , R , R , R , R and R independently represent an alkyl group with 1 to 12 carbon atoms, an alkenyl group with 2 to 8 carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, with * ^7

R° and R ^z independently of each other represent hydrogen, methyl, ethyl, methoxy, ethoxy, fluorine, chlorine, bromine, cyano, nitro, methoxycarbonyl or ethoxycarbonyl, r!0, rH, R ⁴² , r^3 _and p15 _{independently} of each other represent hydrogen, or when Z ⁴ represents a direct bond, they represent in pairs or a -CH=CH-bridge, or

R⁴; R⁵and r8 ; r9 independently of each other in pairs represent -(Cl^^ or -(^2)3- bridge, when Z⁴indicates a direct bond and in this case r69_andr74 independently of each other denote hydrogen or an alkyl group with 1 to 4 carbon atoms,

E ⁴ and E ² are identical and represent 0, S, NR ¹ or C(O1(3)2 or together form a -N-(CH ₂ )2 ^-N_bridge ,

R ⁴ represents an alkyl group with 1 to 12 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms,

Y represents a direct bond -CH=CH-, -C(CH ₃ )=CH-, -C(CN)=CH-, -C^C- or -CH=NN=CH-,

Z ² represents -(CH ₂ ) _r - or -CH ₂ -CgH ₄ -p-CH ₂ -, r represents an integer between 1 and 6,

R ¹⁰¹ to R ¹⁰³ independently represent groups of general formulae

(CXIX), (CXX), in which

R ¹³² and r ¹³³ independently represent hydrogen, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, halogen, cyano, nitro, ·· • « bis-alkylamino group with 1 to 4 carbon atoms in the alkyl, tris-alkylamino group with 1 to 4 carbon atoms in each alkyl, an alkoxycarbonyl group with 1 to 4 carbon atoms in the alkoxy or COOH, or adjacent groups in pairs together form -O-(CH ₂ ) ₂₃ ,

-O-(CH ₂ ) ₁ _ ₂ -O-, NR ¹⁶³ -(CH2)2_3- or NR ¹⁶³ -(CH2) ₁ _ ₂ -O-bridge, or r!58; r159 _and / _{or r} !61; R-*- ³² forms a -CH=CH-CH=CH-bridge, which may be substituted by methyl, ethyl or chlorine, r!63 denotes hydrogen or an alkyl group of 1 to 4 carbon atoms,

E^· ² means 0, S or NR^ ³⁴ ,

R ¹ ^ ⁴ represents hydrogen, an alkyl group with 1 to 18 carbon atoms, an alkenyl group with 2 to 12 carbon atoms, a cycloalkyl group with 4 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms, and

X denotes a colorless anion that is redox-inert under the given conditions,

RED^ represents one of the groups of the anodic redox system of general formula (X), (XI), (XII), (XIII), (XVI), (XVII), (XVIII) or (XX),

R ²⁸ to R ³¹ , R ³⁴ , R ³³ , R ³⁸ , R ³ ^, R ⁴³ , R ³³ and R ³⁴ independently of ·

♦ ·· ♦· ♦· · 9 9 9

9999 999

999 99 99 99

9 9 9 9

99 99 denotes an alkyl group with 1 to 12 carbon atoms, an alkenyl group with 2 to 8 carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms,

R ⁴⁹ to R ⁵² .

,56 and ^R11 independently represent hydrogen, methyl, ethyl, methoxy, ethoxy, fluorine, chlorine, bromine, cyano, nitro, methoxycarbonyl, ethoxycarbonyl or phenyl,

R ⁴ ® additionally denotes NR ² ^r76, o

Z ^J denotes a direct bond or -CH=CH- or -N=N-bridge, =Z ⁴ = denotes a direct double bond, =CH-CH= or =NN= bridge,

E ² to E$, Ε ⁷ θ and E·* ⁴ independently of each other denote 0, S, NR^ ⁹ or E ² and E ⁴ have the same meaning,

E^ to E ⁹ are identical to each other and represent S, Se or NR$ ⁹ , and

E^ additionally denotes C=0,

R ⁵⁹ , R ⁷⁵ and R ⁷ ^ independently of each other denote an alkyl group with 1 to 12 carbon atoms, an alkenyl group with 2 to 8 carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, an arylalkyl group with 7 to 15 carbon atoms or an aryl group with 6 to 10 carbon atoms • · ··· ··* • · · · · · · · · · · • * · ·· ··· • 4 4 · • · 4 4

4 4 4

4 4 4 and

additionally denotes hydrogen or R ²³ and R ² ^ in the definition of nc Ύ

NR ^/J R' , together with the N atom to which they are attached, represent a pyrrolidine, piperidine or morpholine group, r61, r62, r67 _and r68 independently represent hydrogen, an alkyl group with 1 to 4 carbon atoms, methoxycarbonyl, ethoxycarbonyl or phenyl or in pairs form a - (CH2)3- or -(^2)4- bridge, r63 _and ž r66 _ζηει< 5χ hydrogen and v represents an integer from 1 to 6.

Preferably, an electrochromic device is used which contains one of the compounds of general formula (Ia) to (Id), in which

OX2 represents one of the groups of general formula (II), (III), (IV) and (V) where the bond to the bridging member B is through one of the groups R and ^R22 , or when ^E4 or ^E2 represents ^NR2 , it is through R^ and in this case these groups represent a direct bond and all other groups have the meaning given above,

RED^ represents one of the groups of general formula (X), (XI), (XII), (XIII), (XIV), (XVII), (XVIII) and (XX),

9

9

999

9 ·

9 9 9 9

9 9 9 9

9 9 9 9

OO where the bond to the bridging member B is through one of the groups R to R ⁴¹ , R ⁴² to R ²² , R ²¹ , R ⁶² , R ²⁷ and R ⁶⁸ , or when one of the groups E ² to E ¹¹ is NR ²⁹ , it is through R ²⁹ and in this case these groups represent a direct bond and all other groups preferably have the meaning given above, and

B represents the bridge of the general formula

-( ^CHR80 )s-(CH2)n-( ^CHR80 )s-, -(CHR80) _s -( _CH2 ) _m -O-( _CH2 )p-(CHR80 _)s . ₎ -(CHR ⁸⁰ )s-(CH2)m-NR ⁶⁰ -(CH2) _p -(CHR ⁸⁰ ) _s -, -(CHR80) _s -(CH ₂ ) _m -C ₆ H4-(CH ₂ ) _p -(CHR80) _s -, -[O-(CH ₂ ) _p ] _o -O-, -[NR60-(CH ₂ )p] _o -NR60-,

-(CHR ⁸⁰ )s-(CH2)m-OCO-C6H4-COO-(CH2)p-(CHR ⁸ 0)s-,

-(CHR ⁸⁰ ) _s -(CH ₂ ) _m -NHCO-C ₆ H 4 -CONH-(CH ₂ ) _p -(CHRS0) _s -,

-(CHR ⁸ 0) _s -(CH ₂ ) _m -NHCONH-C ₆ H ₄ -NHCONH-(CH ₂ )p-(CHRSO) _s -,

-(CHR ⁸ 0) _s -(CH ₂ ) _m -OCO-(CH ₂ ) _t -COO-(CH ₂ )p-(CHRS0) _s .,

-(CHR ⁸⁰ )s-(CH2)m-NHCO-(CH2)t-CONH-(CH2)p-(CHR ⁸ 0)s-,

-(CHR ⁸ 0)s-(CH2)m-NHCONH-(CH2)t-NHCONH-(CH2)p-(CHR ⁸ 0)s-,

R ⁶⁰ denotes methyl, ethyl, benzyl or phenyl,

R ⁸⁰ represents hydrogen, methyl or ethyl, n represents an integer from 1 to 10, independently of each other represents an integer from 0 to 4, represents an integer from 0 to 2, represents 0 or 1 and • · • · ·

0

4 4

0 0

· 0 0 0 means an integer from 1 to 6

An electrochromic device is also preferably used which contains mixtures of the above-mentioned electrochromic, generally specified and preferably used substances. Examples of such mixtures are (II) + (Cl) + (XVI), (II) + (IV) + (XII), (Ia) + (II) + (XVI), (Ia) + (Cl), without any limitation.

Mixing ratios are variable over a wide range, allowing optimization of the desired shade and/or optimization of the desired dynamic properties of the device.

In the above meanings of the substituents, alkyl groups including modified forms such as alkoxy groups or arylalkyl groups are preferably used, groups with 1 to 12 carbon atoms, in particular groups with 1 to 8 carbon atoms, unless otherwise specified. The groups may be straight or branched and optionally contain further substituents such as alkoxy with 1 to 4 carbon atoms, fluorine, chlorine, hydroxyl, cyano, alkoxycarbonyl with 1 to 4 carbon atoms or COOH.

Cycloalkyl groups are preferably groups with 3 to 7 carbon atoms, especially with 5 or 6 carbon atoms.

Alkenyl groups are preferably groups with 2 to 8 carbon atoms, especially with 2 to 4 carbon atoms.

Aryl groups including arylalkyl groups are phenyl or naphthyl groups, especially phenyl groups. They may be substituted with 1 to 3 of the following groups: alkyl group with 1 to 6 carbon atoms, alkoxy group • · ·· • · · • φφφ· φφ ·· φ φ · φ φ φ φ · · with 1 to 6 carbon atoms, fluorine, chlorine, bromine, cyano, hydroxyl, alkoxycarbonyl group with 1 to 6 carbon atoms or nitro group. Two adjacent groups may also form a ring.

Optional benzofused aromatic or quasi-aromatic five- or six-membered heterocyclic rings are in particular imidazole, benzimidazole, oxazole, benzoxazole, thiazole, benzothiazole, indole, pyrazole, triazole, thiophene, isothiazole, benzisothiazole, 1,3,4- or 1,2,4-thiadiazole, pyridine, quinoline, pyrimidine or pyrazine. They may be substituted by 1 to 3 of the following groups: alkyl group with 1 to 6 carbon atoms, alkoxy group with 1 to 6 carbon atoms, fluorine, chlorine, bromine, cyano, nitro, hydroxyl, mono- or di-alkylamino group with 1 to 6 carbon atoms in each alkyl, alkoxycarbonyl group with 1 to 6 carbon atoms, alkylsulfonyl group with 1 to 6 carbon atoms, alkanoylamino group with 1 to 6 carbon atoms, phenyl or naphthyl. Two adjacent groups can also form a circle.

Electrochromic substances are either known (Topics in Current Chemistry, Vol. 92, pp. 1-44, (1980), Angew. Chem. 90, 927 (1978), Adv. Mater. 3, 225, (1991), DE-A 3,917,323, J. Am. Chem. Soc. 117, 8528 (1995), J. C. S. Perkin II 1990, 1777, DE-A 4,435,211, EP-A 476,456, EP-A 476,547, DE-A 4,007,058, J. Org. Chem. 57, 1849 (1992) and J. Am. Chem. Soc. 99, 6120, 6122 (1977)) or can be prepared analogously. Compounds of general formula (I) can be synthetically prepared from building blocks that are known individually, for example according to the following scheme:

Br

Ions resulting from the synthesis, such as bromide, are subsequently exchanged for redox-inert ions.

The electrochromic display device of the invention comprises at least one solvent in which electrochromic substances, preferably conductive salts and preferably other additives, are dissolved. The solvent may also be thickened into a gel form using, for example, polyelectrolytes, porous solids or nanoparticles with a large active surface area.

Suitable solvents are all solvents which are redox-inert at the selected voltages and which are not capable of releasing any electrophiles or nucleophiles or of reacting themselves as sufficiently strong electrophiles or nucleophiles and thus reacting with colored ionic groups.

Examples are propylene carbonate, t-butyrolacetone, acetonitrile, propionitrile, glutaronitrile, methylglutaronitrile, 3,3'-oxydipropionitrile, hydroxypropionitrile, dimethylformamide, N-methylpyrrolidine, sulfolane, 3-methylsulfolane or mixtures thereof. Propylene carbonate and mixtures thereof with glutaronitrile or 3-methylsulfolane are preferably used.

The electrochromic solution according to the invention may contain * ·« ♦· ·· ·· ·♦ • · · · · · r · · 9 · • · · · ··· · ·· · z ··· · · «· _· * · · · · • · _··

Lithium, sodium and tetraalkylammonium salts, especially the latter, are suitable as inert conducting salts. The alkyl groups may have between 1 and 18 carbon atoms and may be identical or different. Tetrabutylammonium is preferably used. Suitable anions for these salts, which are also suitable as anions X in the general formulas (II) to (VI), (CI), (CH) and (CV) to (CVII) in the metal salts, are all redox-inert, colorless anions.

Examples are tetrafluoroborate, tetraphenylborate, cyanotriphenylborate, tetramethoxyborate, tetrapropoxyborate, tetraphenoxyborate, perchlorate, chloride, nitrate, sulfate, phosphate, methanesulfonate, ethanesulfonate, tetradecanesulfonate, pentadecanesulfonate, trifluoromethanesulfonate, perfluorobutanesulfonate, perfluorooctanesulfonate, benzenesulfonate, chlorobenzenesulfonate, toluenesulfonate, butylbenzenesulfonate, tertiary butylbenzenesulfonate, dodecylbenzenesulfonate, trifluoromethylbenzenesulfonate, hexafluorophosphate, hexafluoroarsenate, hexafluorosilicate, 7,8- or 7,9-dicarbanido undecaborate (-1) or (-2), which are preferably substituted on the B and/or C atoms by one or two methyl, ethyl, butyl or phenyl groups, dodecahydro-dicarbadodecaborate (-2) or B-methyl-C-phenyl-dodecahydro-dicarbadodecaborate (-1).

Conductive salts are preferably used in the range of 0 to 1 mol/l.

Other additives used may be thickeners to control the viscosity of the electroactive solution. This may be

69 • · 9 • · · * · · 4 · • · *· • 4 4 99

Φ · · • 9 9

49 • · 94

4 9 4

4 4 4

6 4 9 9 4

9 4 9 9

46 important for eliminating segregation, i.e. the formation of colored stripes or spots during prolonged operation of the electrochromic device in the switched-on state, and for controlling the bleaching rate after the power is turned off.

Suitable thickeners are all compounds customary for this purpose, such as, for example, polyacrylate, polymethacrylate (Luctite ^LR ), polycarbonate or polyurethane.

Other additives suitable for the electrochromic fluid and to increase UV protection in certain cases are UV absorbers. Examples are UVINUL ^R 3000 (2,4-dihydroxybenzophenone, BASF), SANDUVOR ^R 3035 (2-hydroxy-4-n-octyloxybenzophenone, Clariant), Tinuvin ^R 571 (2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, Ciba), Cyasorb 24^ (2,2'-dihydroxy-4-methoxybenzophenone, American Cyanamid Company), UVINUL ^R 3035 (ethyl 2-cyano-3,3'-diphenylacrylate, BASF), UVINUL ^R 3039 (2-ethylhexyl-2-cyano-3,3-diphenylacrylate, BASF),

UVINUL ^R 3088 (2-ethylhexyl p-methoxycinnamate, BASF) and CHIMASSORB ^R 90 (2-hydoxy-4-methoxybenzophenone, Ciba).

Preferably, the last four absorbers are used. Mixtures of UV absorbers are also preferably used, examples being mixtures of the last four absorbers. Preferably, a mixture of UVINUL ^R 3039 (BASF) and CHIMASSORB ^R 90 is used.

UV absorbers are used in the range from 0.01 to 2 mol/l, preferably from 0.04 to 1 mol/l.

The electrochromic solution contains electrochromic substances OX2 and RED^, in particular substances of the general formulae (I) to (XX) and (Cl) to (CIV), in each case in a concentration of at least 10-4, preferably from 0.001 to 0.5 mol/l. The total concentration of all electrochromic substances present is below 1 mol/l.

The electrochromic device according to the invention is operated by means of a constant, pulsed or amplitude-variable, for example sinusoidal, direct current. The voltage depends on the desired depth of color, in particular on the reduction or oxidation potentials of the OX ₂ and RED^ substances used. These potentials can be found, for example, in the publication Topics in Current Chemistry, Volume 92, pp. 1-44, (1980) or

Angew. Chem. 90., 927 (1978) or the literature cited therein. The difference in their potentials is a guiding parameter for the required voltage, although the electrochromic device can be operated even at a lower voltage or also at a higher voltage. In many cases, for example when using OX ₂ = formula (II) or (IV) and RED-^ = formula (X), (XII), (XVI) or (XVII) or their forms, connected via a bridge according to formula (I), in particular formulas (la) to (Id), this potential difference required for operation is < 1 V. These electrochromic devices can therefore be powered in a simple manner by current from silicon photovoltaic cells.

When the voltage is switched off, the electrochromic device according to the invention returns to its original state. This erasure can be greatly accelerated if the contacted segments and/or plates are short-circuited. The display can also be erased very quickly by multiple reversals of the voltage polarity without or with simultaneous reduction of the voltage.

By varying the thickness of the electrochromic device layer, the viscosity of the electrochromic solution, and/or the diffusion or entrainment power of the electrochromic substances, it is possible to influence the on and off times of the display device over a wide range. For example, thin layers exhibit shorter switching times than « · 4 • · ·

4 4

4 44 thick layers. Therefore, it is possible to design fast and slow switching devices and thus adapt them to the respective end-use requirements.

In the case of slow devices, especially display devices, a current saving method or a refresh method can be used to keep the displayed information in the on state. After the information to be displayed has been set, for example, by using a constant or pulsed direct current voltage or a direct current voltage that varies with a high frequency, said voltage being in all cases of sufficient magnitude, the device is switched to a pulsed or variable direct current voltage of low frequency by contacting the segments that are not short-circuited during the phases in which the voltage is zero. This low frequency can be, for example, in the region of 1 Hz or lower, and the duration of the on and off phases need not be of equal length, but instead it is possible, for example, for the off phases to be considerably longer. Since the color depth of the displayed information is slowly lost during the interruption of the current in the unshorted state, relatively short current pulses are sufficient to compensate for these losses again in the following refresh phase. In this way, a flicker-free and flicker-free image with a virtually constant color depth is obtained, which nevertheless requires only a fraction of the current that would be consumed if the current flow were continuous.

The nanoparticle-based UV absorbers of the invention can be in a homogeneous dispersion in an electrochromic system, for example in an electrochromic solution. They can also be uniformly distributed in systems of electrochromic layers that are placed on a conductive layer. These layers can be applied by doctor blade coating or cast from solution, in

X in which the nanoparticles are in dispersion and the electrochromic substance is in solution or also in dispersion. By removing the solvent, an electrochromic layer is then obtained which contains the nanoparticles. Alternatively, the nanoparticles can be uniformly distributed in a polymer or coating material, wherein the polymer or coating material is applied as a coating layer on at least one of the two plates or films.

As a further possibility, nanoparticles may be present in sheets or films, particularly when these sheets or films consist of plastics.

Furthermore, all these forms of nanoparticles used can be combined, that is, the nanoparticles are present both in the electrochromic system and in one of the described layers and/or in the plates or foils.

The electrochromic system or any of the described polymer or coating materials of the layers or glass plates or plastic plates or foils of the electrochromic device contains a nanoparticle-based UV absorber according to the invention in a concentration of from 0.001 to 30 atomic %, preferably from 0.01 to 10 atomic %.

Polymers and coating materials can be, for example, polycarbonate, polyurethane, polyester, polyimide, polyamide, acrylates or polyacrylonitrile. Nanoparticles can be incorporated into these materials using conventional methods, for example according to WO-A 95/09 895, WO-A 92/21 315 or EP-A 0 628 303.

Specific configurations of the above types 1 and 2 may be, for example, the following and are also subject to the invention when protected by nanoparticles against UV radiation.

Type 1: (without mirror coating)

From the field of light protection/light filters: window panes for example for buildings, motor vehicles, aircraft, trains, ships, glass roofs, sliding roofs of cars, glazing of greenhouses and winter gardens, light filters of any type;

From the field of security/secrecy: separation partitions, for example, for rooms in offices, motor vehicles, aircraft, trains, transparent protective partitions in banks, glass doors, visors for motorcycle or pilot helmets;

From the field of design: glazing of bakery ovens, microwave ovens, other household appliances, furniture.

Type 1: (equipped with mirrors)

Mirrors of any type, for example for motor vehicles, trains, especially plane, spherical and aspherical mirrors and their combinations, e.g. glazing of furniture with spherical/aspherical mirrors.

Type 2:

Display devices of any type, for example segmented or matrix displays for watches, computers, electrical appliances, electronic devices such as radios, amplifiers, televisions, CD players, etc., station displays in buses and trains, departure displays in railway stations and airports, flat screens, all appli* « • * • »4 4 · · · ·

00 ·4 4« cations, specified in types 1 and 2, which include at least one switchable, static or variable display device, for example, partition partitions that include displays such as Please Do Not Disturb, Partition Occupied, or for example, automotive mirrors that include displays of any desired type, such as displays of temperature, vehicle faults (e.g. oil temperature, open door), time, directions and the like.

Examples of embodiments of the invention

Example 1

The cell was constructed according to Fig. 1. For this purpose, two glass plates 1 and 2 were used, coated on one side with ITO. On the other side, the plates were provided with a layer containing Ce0 ₂ nanoparticles. The layer was applied in the following manner. First, a polyvinyl alcohol solution with a concentration of 6% by weight and a Ce0 ₂ dispersion with a concentration of 7% by weight were prepared, in both cases in water. Ce0 ₂ nanoparticles were obtained from Rhodia, Frankfurt and have a size distribution of 8 ± 2 nm. These solutions were mixed in a 1:1 ratio. The mixture is a polyvinyl alcohol solution with a concentration of 4% by weight with a Ce0 ₂ fraction corresponding to 20% by weight, based on the total solids fraction.

A mixture of 97% photocurable DELO-Katiobond^ 4594 epoxy adhesive (DĚLO-Industrieklebstoffe, Landsberg) and 3% glass beads with a diameter of 200 gm was applied in the form of a ring 3 to the ITO-coated side of a glass plate 1 in such a way that a 2 mm wide opening remained • 4 • · 4444 444

44444 44 44 ·· ♦· . The glass plate 2 was then placed on the bead of adhesive in such a way that the ITO layers of the two plates X and 2 were facing each other, creating the geometry shown in Fig. 1. The adhesive was cured by exposure to daylight for 10 minutes near a window and then for 20 minutes at 105°C without exposure.

The vessel was filled in a nitrogen atmosphere with a 0.02 molar solution of an electrochromic compound of the formula

in anhydrous, oxygen-free propylene carbonate.

The cell was then placed vertically in a container under a nitrogen atmosphere in such a way that the opening 4 was located below the liquid level. The container with the cell was placed in a desiccator. The desiccator was evacuated to a pressure of 5 Pa and then carefully filled with nitrogen. During the filling, the electrochromic solution penetrated through the opening 4 into the cell and filled the entire volume except for small bubbles. The cell was removed from the solution, the opening 4 was cleaned in a nitrogen atmosphere by wiping with a paper towel and sealed with the photochemically curable acrylic adhesive DELO-Photobond^ (DĚLO-Industrieklebstoffe, Landsberg).

Subsequently, the cell was exposed for 1 minute in a nitrogen atmosphere using a DELOLUX^ 03 bulb (DELO-In47 ···· ··· « • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·♦·· · · · · · · · · · * * ·· dustrieklebstoffe (Landsberg) at a distance of 8 cm from the hole and was cured at room temperature overnight in a nitrogen atmosphere.

Applying a voltage of 0.9 V to both plates 1 and 2 caused the cell to quickly change color to a strong greenish-blue. Turning off the voltage and shorting the contacts caused the color to disappear again quickly.

Example la (Comparative)

The cell was constructed as in Example 1, but using glass plates coated only with ITO.

Light stability test

To test the light stability, the cells described in Example 1, together with the reference cells described in Example 1a, were exposed at an operating voltage of 0.9 V in a Suntest CPS+ test device from Atlas, Linsengericht-Altenhapiau, equipped with a cup-shaped filter element.

By plate A and using an irradiation power of 765 V/m.

Before the start of irradiation, the absorption spectrum of each cell was recorded in the on (0.9 V) and off (0 V) states using a Cary AG absorption photometer (Varian, Darmstadt).

Irradiation was carried out at intervals that at least doubled (30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 16 hours), so that each sample was irradiated after • 4 4 4 i

4 for a total time of 183.5 hours at the end. After each irradiation interval, absorption measurements were again taken in the on and off states. These measurements were used to create a difference spectrum, which is the instantaneous spectrum that is recorded minus the initial spectrum in both states, i.e., the on and off states.

Cell damage was determined by a decrease in the electrochromic shift range. This means a decrease in the change in transmittance at a given wavelength.

The maximum wavelength at 605 nm was evaluated.

When evaluating the difference spectrum, it is necessary to take into account the fact that changes in transmission in the off state will also appear in the difference spectrum of the on state, where they should be subtracted.

The following table shows the reduction in electrochromic shift range over cumulative irradiation time for a cell of the invention with nanoparticles (as described in Example 1) and for comparison a cell without nanoparticles (as described in Example 1a).

Comparison with cells without nanoparticles shows a strong increase in stability.

In % 0 hours 0.5 hours 1.5 hours 3.5 hours 7.5 hours 15.5 hrs 39.5 hours 87.5 hours 183.5 hours Article with nanoparticles 100 100 100 100 97 96 88 81 49 A cell without nanoparticles 100 68 49 40 32

» · · 1 > 9 9 4

9* 99

Cell damage (20% lower electrochromic shift) was detected after 78 hours. This represents an improvement of a factor of 250 compared to the unprotected state.

Claims (24)

1. Electrochromic devices against UV radiation. 2. Electrochromic equipment, CLAIMS which are protected by a nanopart consisting of two plates or foils of which at least one is transparent and which are provided with a conductive layer on their facing sides, at least one conductive layer is transparent and interconnected by a sealing ring, the plates or foils and the sealing ring define a volume within which an electrochromic medium is contained, characterized in that the electrochromic device is protected by nanoparticles against UV radiation. Electrochromic device according to claim 2, characterized in that at least one of the two conductive layers is coated with an electrochromic layer. 4. The electrochromic device of claim 2, wherein the electrochromic medium is an electrochromic solution. Electrochromic device according to one or more of Claims 1 to 4, characterized in that the nanoparticles are contained in an electrochromic system and / or are deposited on at least one of the two plates or sheets and / or embedded in at least one of the two plates or the sheets or sheets being transparent. 6. Electrochromic device according to one or more of the claims I • 4 43 • 4 4 · 4 4 4 4 • · · 9 4 4 4 4 4 44 44 1 to 4, characterized in that the nanoparticles are dispersed in an electrochromic system. Electrochromic device according to one or more of Claims 1 to 4, characterized in that the nanoparticles are contained in a coating applied to at least one of the two plates or foils. Electrochromic device according to one or more of Claims 1 to 4, characterized in that the nanoparticles are embedded in at least one of the two plates or films. Electrochromic device according to one or more of Claims 1 to 8, characterized in that the nanoparticles are made of materials based on SiC, AISi, Fe ₂ O ₃ , Fe ₃ O ₄ , TiO ₂ , ZnO, GaP, CeO ₂ , ZnS , SnO ₂ , Si _y Ge ₁ _ _y , ν _χ ο ₁ _ _χ 0 ₃ , NiO, Bi ₂ O ₃ , In ₂ O ₃ , HfO ₂ , BaTiO ₃ , CaTiO ₃ , Ge, AIP, GaN, in which 0.7 <y <1 and 0 <χ <1. Electrochromic device according to one or more of Claims 1 to 8, characterized in that the nanoparticles consist of materials based on SiC, AISi, a silver halide emulsion layer, Fe ₂ O ₃ , Fe ₃ 0 ₄ , TiO ₂ , ZnO, CeO. ₂ , ν _χ Μο ₂ _ _χ 0 ₃ , BaTiO ₃ and CaTiO ₃ , in which 0 <x <1. Electrochromic device according to one or more of Claims 1 to 10, characterized in that the nanoparticles consist predominantly of silicon and / or solid compounds in which the silicon is present in a stoichiometric excess. Electrochromic device according to one or more of Claims 1 to 11, characterized in that the nanoparticles have a mean diameter of less than 500 nm, preferably <100 nm, at a diameter of less than 500 nm. 4 4 9443 4 44 4 444 94 44 444 44 4 4449 4949 494 «44 44 94 44 particularly preferably <50 nm and very particularly preferably 20 20 nm. Electrochromic device according to one or more of claims 1 to 11, characterized in that the nanoparticles are spherical or nearly spherical. Electrochromic device according to one or more of claims 1 to 13, characterized in that the nanoparticles have a shell core structure. Electrochromic device according to one or more of Claims 1 to 14, characterized in that the shell is organically modified. Electrochromic device according to one or more of Claims 1 to 15, characterized in that the solid compounds in which the silicon is present in a stoichiometric excess are compounds of the general formula Si _x Z _4x , in which 0,5 <χ <1 aZ represents C, N, O, Ge, Ca, Ba or Sr or mixtures thereof. 17. Electrochromic device according to one or more of claims 1 to 16, characterized in that the solid compounds in which the silicon is present in a stoichiometric excess have a shell core structure. Electrochromic device according to one or more of Claims 1 to 17, characterized in that the nanoparticles consist of a titanium nitride core and a silicon shell, the silicon by volume being at least 30% by volume, based on the nanoparticles. 19 Dec Electrochromic device according to one or more of the claims Iv »» »» »» »« · «» »» «« • • • · · • • • • • • • · · .. · ·················· 1 to 18, characterized in that the nanoparticles have a particle size distribution with a maximum center peak width of 40 nm, preferably 30 nm and particularly preferably 20 nm. Electrochromic device according to one or more of claims 1 to 19, characterized in that the nanoparticles are coated with an oxide layer with a thickness of 1 to 300 nm. Electrochromic device according to one or more of Claims 1 to 20, characterized in that the shell is an oxide of nanoparticle material or consists of another material which is transparent in the visible range and whose refractive index is similar to that of nanoparticles. Electrochromic device according to one or more of Claims 1 to 21, characterized in that particles of metal oxides and / or metal nitrides are additionally admixed with these nanoparticles which absorb much more in the red spectral range of 600 nm <lambda <700 nm than in blue-green spectral range 400 nm <lambda <550 nm. Electrochromic device according to one or more of Claims 1 to 22, characterized in that the additional particles to be added consist of titanium nitride with an average particle diameter of from 1 to 400 nm, preferably from 1 to 100 nm and particularly preferably from 1 to 50 nm or are agglomerates of these primary titanium nitride particles. Electrochromic device according to one or more of Claims 1 to 23, characterized in that the additionally added particles are aluminum-sodium silicates.